When items such as pallets are transported, they cannot necessarily rely on their own weight and that of the cargo that they carry to keep them fixed. They have to be constrained in some way. Traditionally, they have been lashed down by tensioned ropes, wires or chains, but those take time to set up and undo, and they are wasteful of space since there has to be room around the pallet. Also, the lashings are often directed over the cargo and so they compress the cargo. The loaded pallets are not easy to stack one on another.
To make stacking easier, pallet racks have been employed, but then the racks have to be restrained. Restraining cargo or items such as pallets can be even more problematic when the racks are on board moving aircraft and are subjected to considerable forces, e.g. 3-5 G. Usually, a large number of ropes, etc are required to tie the items in this situation, but this takes up a considerable amount of time and means that removing the pallets is also an awkward and time-consuming process. This is clearly disadvantageous when the contents need to be unloaded quickly in an emergency situation. Some parts, especially wheels on which the pallets can roll out that are not specially constructed to withstand the high forces can also bend, which can cause the pallet or the like to become stuck in the rack.
One attempt to overcome the problems mentioned is commercially available. In that product, transportation and storage equipment is used having elements including an outer container, a support device for fitting inside the container for removably holding a cargo or load rack. The rack and device are clamped together using a rotatable mechanism, which can be difficult to undo in use and requires regular maintenance and lubrication.